Generally speaking, the present application relates to a color changeable dye that changes color after being exposed to oxygen for a predetermined period of time. The color changeable dye is intended for use on disposable, limited or restricted use products that can transmit contaminants, and disease to a person or cause infection if reused or used beyond a recommended period of time. The color changeable dye acts to indicate that the product should no longer be used. The present application also relates to methods of making and using the color changeable dye and apparatuses incorporating the color changeable dye.
Many products currently marketed and sold to consumers are designed for limited use. These products are usually associated with a single event, a restricted time period or restricted access. There are many reasons for the need of single use or limited use products.
There are numerous examples of single use products in the medical field. One example is a disposable syringe. Instrument contamination and cross infection between patients is an ever present concern if the syringe is inadvertently reused. It is a particular concern in some countries where repeated use of instruments is known to transmit serious diseases such as HIV and hepatitis. Medical and ophthalmic devices that must be sterilized such as scalpels or tonometers (e.g., for the measurement of a patient's intraocular pressure) body piercing and tattooing instruments used on multiple clients also give cause for concern. Needles used in acupuncture offer another example. Decontamination procedures or employment of single-use devices are methods used to control cross infection, but they rely on personnel awareness, willingness to follow protocol, monitoring and documentation.
The limited use type of product is usually associated with goods that should be used for a restricted time period. One example of this type of product is “daily wear” or disposable contact lenses. Contact lenses for refractive correction or cosmetic purposes require suitable wear and care regimes in order to maintain good eye health. Non-compliance on the part of the patient, either through choice or due to lack of education, can injure the eye. Frequent replacement lenses are sometimes worn for longer than recommended or they may be stored or cleaned inappropriately.
U.S. Pub. No. 2009/0303440, which is co-owned by applicant and incorporated herein in its entirety by reference, previously addressed a similar problem. U.S. Pub. No. 2009/0303440 presented a disposable limited or restricted use apparatus that includes a color changeable portion wherein the time that the color change occurs is controlled so that it coincides to the approximate time of the end of one use of a single use apparatus or to the approximate expiration time for extended but limited or restricted use apparatus.
The present application provides the additional benefit of allowing the color changeable dye to be applied to a disposable limited or restricted use apparatus in the presence of oxygen in its oxidized state in a first color. It can then later be reduced after the disposable limited or restricted use apparatus has been packaged in a substantially oxygen free environment to its reduced state in a second color. This allows the color changeable dye of the present application to be applied in the presence of oxygen rather than in a substantially oxygen free argon environment.